Telephone-transmitter



(No Model.) G. W. SMITH.

Telephone Transmitter.

No. 235,707. Patented Dec. 21,1880

N. PETERS, PHOTO-LITHDGRAPHER, WASHINGT ON o. c.

IJNITED STATES PATENT OFFICE.

GEORGE W. SMITH, OF NEW HARTFORD, CONNECTICUT.

TELEPHON E-TRANSM ITTER.

SPECIFICATION forming part of Letters Patent No. 235,707, dated December21, 1880.

Application filed July 20, 1880. (No model.)

To all whom t't may concern:

Be it known that I, GEORGE W. SMITH, residing in the town of NewHartford, county of Litchtield, and State of Connecticut, have inventeda new and useful Improvement in Telephone-Transmitters; and I do herebydeclare that the following is a full, clear, and ex act descriptionthereof, reference being bad to the accompanying drawings, making a partof this specification. Y

My invention relates to that class 'of transmitters employing a localbattery and an induction-coil.

In the accompanying drawings, Figure 1 is a plan of the transmitter withthe top removed. Fig.2 is a sectional view of the above, and also showsthe top of the case and the mouth-piece.

C is a block of carbon, glued or otherwise attached to the bottom of thebox or case of the transmitter.

D is the diaphragm, consisting of a strip of copper, brass, or olhermetal, attached to a block, B, of somenon-conducting substanceas woodbymeans of the screw S.

I is a spring fastened at A, and having one end resting upon tlfemetallic strip D, the object of which is to deaden any tones whichotiiferwise might be given out by the metal itse One of the wires isattached directly to the carbon, as showuat W, the other connectionbeing made at V with the metallic strip form ing the diaphragm.

Carbon transmitters, as heretofore made, have been more or lesscomplicated in construction, generally consisting of a thin disk orplate of carbon combined with some metal, as platinum-foil, and suchplate of carbon, being very liable to break, also required protection.

My invention or transmitter is simpler in construction and less liableto be injured by use. It consists simply of a block of carbon, C,fastened directly to the bottom of the box or case of the transmitter.The carbon may be glued to the case, but any suitable means ofattachment may be used.

Resting at one end directly upon the carbon itself is the diaphragm D,consisting of a strip of copper, the other end of which is fastened to anon-conducting support (shown at B) by means of a screw, S. Thisdiaphragm may be attached to the sides of the case, or in any way mostconvenient, it only being essential that it is fastened in such a waythat its normal pressure upon the carbon may be adjusted by tighteningor loosening the screw fastening it at its other end.

In place of copper I have employed as a diaphragm strips of brass orother metal.

It will be ObSGlWd that in my transmitter the diaphragm itself is indirect contact with the carbon, there being no intervening substancebetween the two, and that the wires are attached respectively to thecarbon and to the metallic strip forming the diaphragm. By this means Iproduce a transmitter both simpler and cheaper in construction and alsomore reliable in action.

In order to destroy any sound given out by.

the strip or diaphragm and make the sounds transmitted clearer, I employa spring, which rests upon the diaphragm, as shown at I, and destroysany vibrations produced in the metal itself.

I prefer to use a block of pure carbon but prepared carbon made in anysuitable form may be employed.

\Vhen words are spoken or sounds made in the vicinity of the mouth-pieceof the transmitter the metallic strip or diaphragm D is thrown intovibrations, which vary the resistance of the carbon, and thus controlthe current transmitting the sound.

What I claim, and desire to secure by Letters Patent, is

1. In atelephonic transmitter, acarbon block or disk, orits equivalent,and a metallic strip, forming the diaphragm, resting directly upon thecarbon, the pressure of which is regulated by a screw at its fartherend, substantially as and for the purpose set forth.

2. In a telephonic transmitter, the combination of the carbon block, thecopper strip D,

and the spring 1 substantially as described.

GEO. W. SMITH. Witnesses: CHAs. B. WHEELER, J. L. WOODRUFF.

